Speaker
Description
We study the exclusive semileptonic $B_c\to D_s^{(*)} (\mu^+ \mu^-, \nu \bar{\nu})$ decay modes mediated by $b \to s$ quark level transitions in the Effective field theory formalism. There are discrepancies between the experimental measurements and the Standard Model predictions in various observables associated with the $B \to (K, K^*, \phi)\ell \ell$ processes. On the other hand, a very recent measurement of the branching ratio of the $B \to K \nu _\ell \bar{\nu}_\ell$ process observed by Belle - II Collaboration indicates a $2.8 \sigma$ deviation above the Standard model prediction. We constraint the parameter space in the language of new physics couplings and then analyse the observables such as the branching ratio, forward-backwards asymmetry, lepton polarisation asymmetry, etc. In addition, we test the lepton non-universality observable associated with the $B_c\to D_s^{(*)} \mu^+ \mu^-$ process. Being not yet observed in the experiment, we provide the predictions and comment on the observables of the $B_c\to D_s^{(*)} (\mu^+ \mu^-, \nu _\mu \bar{\nu}_\mu)$ process in the SM, and in the new physics as well.
